I had no idea. Still don't. (I can't even make out what's written on them! You're talking about the necklace like gear, yeah?)

Bunches of speculation, still ongoing:

The equation at the front seem to be the Schwarzschild metric and relates to the Schwarzschild radius, where the event horizon of a black hole is found. I’ll let wikipedia step in here.

“The Schwarzschild black hole is characterized by a surrounding spherical boundary, called the event horizon, which is situated at the Schwarzschild radius, often called the radius of a black hole.”

The equation at the back is the Dirac equation, described by redditor tedward27 thusly, “In quantum mechanics, quantum objects and systems are described by something called their wavefunction. The wavefunction encodes information about the probability of finding the system in a certain state (like where a particle is, or how much energy a system has).

“The wavefunction is described by Schrodinger’s equation (that is, given a physical situation, the S. equation is the partial differential equation you need to solve to find the form of the wavefunction). The Dirac equation aims to do the same thing, but this time accounting for special relativity, which the Schrodinger equation completely ignores.

“Special relativity is a theory put forth by Einstein that posits that the speed of light is a constant in all moving or non-moving frames of reference. The consequences of this are such phenomena as length contraction and time dilation when moving at appreciably large speeds relative to another observer.

“Another implication is that there are no special “non-moving” frames of reference (despite what I just said); your measurements in your frame are relative to another observer’s measurements in their frame. As you can imagine, mixing up special relativity and quantum mechanics can be tricky and it took a fairly smart guy (Dirac) to get it right.”

I’m getting black holes and time travelling from all of this.

Interestingly, when you head to Kojima Productions site, the first image you’re presented with is this one:

Now while Ludens is the name of the studio’s “icon”, and the whole Homo Ludens references the play element of culture, with the website’s message being, “We are Homo Ludens (Those who play)”, the Ludens are also a humanoid race from the Noon Universe, the setting for a series of Russian hard sci-fi novels.

The Ludens appear in the novel The Time Wanderers and have basically been experimenting on humans and altering their minds.

There’s a distinct sci-fi/ psychological theme in the trailer, with the disappearing baby and those fancy glowing handcuffs.

So is this another clue hiding in plain sight, or it could be a load of old todgers? Although combined with the speculation that the face of Ludens looks a lot like Norman Reedus, Kojima could be toying with us all.